Heart Development - Severson

Question 1

During a myocardial infarction it is actually possible to get referred pain in the neck and even the angle of the mandible. What developmental process is responsible for this phenomenon?

Answer 1

Neural crest cells from cervical and thoracic regions migrate into developing cardiac structures and innervate them. (visceral sensory and autonomic motor)

Remember the answer is always neural crest cells!

Question 2

There are 3 developing venous systems in the embryo. The Vitelline veins, the umbilical veins, and the cardinal veins.
The azygous vein is derived from which embryonic system?

Answer 2

The cardinal vein system. This system is responsible for drainign the caval system.

Vitelline = forms portal system
Umbilical = drain the placenta

Question 3

In the developing heart tube blood drains into the ________ from the vitelline, umbilical, and cardinal veins before then moving into the atrium, ventricle, bulbous cordis, and finally the truncus arteriosus.

Answer 3

Sinus venosus

Veinous systems -> sinus venosus -> atrium -> ventricle -> bulbous cordis -> truncus arteriosus

Question 4

Just to make sure you’ve got this who circulation thing in the developing embryo, let’s review:

Veinous blood enters the heart tube through the ________ and then leaves the heart tube through the ___________.

Answer 4

Sinus venosus

Truncus arteriosus

Question 5

In heart tube development, the tube must bend to form it’s standard appearance. Which way does it bend? If it bends the wrong way what happens

Answer 5

To the right! (is right…)

To the left is bad… mostly
Dextrocardia occurs. The heart and its vessels are reversed left to right in a mirror image.

Dextrocardia WITH Situs invertus is associated with fewer cardiac defects. This just means that the viscera is also transposed.

Question 6

Endocardial cushions contribute to the developments of which valve(s)?

Answer 6

The tricuscpid and mitral valves

Question 7

Endocardial cushion problems also contribute to which of these developmental abnormalities?

• Persistent atrioventricular canal
• Atrial Septal Defect
• Ventricular Septal Defect

Answer 7

All of these!

• Persistent atrioventricular canal
• Atrial Septal Defect
• Ventricular Septal Defect

Question 8

What is the name of the opening between the septum primum and the early septum secundum?

Answer 8

Foramen secundum

Question 9

What is the name of the opening between the septum primum and the fully formed septum secundum?

Answer 9

Foramen ovale

Question 10

What is the name for the opening between the septum primum and the endocardial cushion?

Answer 10

The foramen primum

Question 11

The bulbar and truncal ridges are derived from what?

They then become what?

Answer 11

Derived from: Neural crest mesenchyme!

Bulbus cordis becomes: conus arteriosus and aortic vestibule
Truncus arteriosus becomes: ascending aorta and pulmonary trunk

(together they also from the aorticopulmonary septum)

Question 12

What do the right and left 4th aortic arches give rise to?

Answer 12

Left 4th Arch = aortic arch

Right 4th Arch = Right subclavian artery

Question 13

The ductus arteriosus is an important anatomical feature in development because it connects the left pulmonary artery to the aorta. A problem with which specific part of which aortic arch would cause problems with the formation of the ductus arteriosis?

Answer 13

The distal portion of the LEFT 6th aortic arch.

after birth will be the ligamentum arteriosum

Question 14

What is formed from the proximal portion of the LEFT 6th aortic arch?

Answer 14

The proximal portion of the left pulmonary artery

Question 15

Explain in your own words the magic of the ductus venosus:

Answer 15

Well it’s pretty great because it is taking oygenated blood from the umbilical vein and then sending it straight through the liver into the inferior vena cava. It’s just pretty smart because we want that oxygenated blood heading straight to the right atrium as soon as possible. This a temporary detour that works great.

Question 16

Where does most of the blood go as it enters the right atrium from the umbilical vein?

Answer 16

Yet another temporary detour has been set up to shunt blood directly from the right atrium to the left atrium where it can enter the left ventricle and be transported to the rest of the body.

Some will end up getting mixed with deoxygneated blood from the superior vena cava and will be sent out the pulmonary trunk.

Question 17

Let’s talk about where blood goes when it leaves the pulmonary trunk. Any magic going on there?

Answer 17

So much magic. As blood comes out the pulmonary trunk, some goes straight into the lungs, but the interesting thing is that most goes through the ductus arteriosus into the descending aorta (Another crazy fetal detour, I know!)

The blood can then travel into the lower extremities and also down through the umbilical arteries and back through the placenta!
Magic.

Question 18

So what happens to fetal circulation when a child is born?

What roads shut down?
How are they now known?

Answer 18

It’s like after construction season ends. All the detours shut down.

-The foramen ovale closes -> forms fossa ovalis (from 2ndary septum)
-Ductus arteriosus closes -> forms ligamentum arteriosum
-Umbilical vein closes -> forms round ligament of the liver
-Umbilical arteries -> distal part forms medical umbilical ligaments AND proximal part remains as superior vesical arteries
-Ductus venosus closes -> forms ligamentum venosum
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